Metal wire is formed by a drawing process which causes the metal to harden and to lose some of its elasticity. In order to soften the wire and thus restore its flexibility, the drawn wire is annealed as part of the overall wire-making process. Annealing involves rapidly heating a section of the wire, after which the heated wire must be cooled.
Usually, annealing of wire is done by electricity. An electric current is either run through a portion of the drawn wire, which acts as a short circuit, or a current is induced in a portion of the drawn wire by a transformer-type arrangement with the portion of the wire to be treated acting as a secondary transformer winding. In either case, the resulting current through the selected portion of the wire causes its temperature to increase, and the wire softens. Most often, this process take place continuously as the wire travels between and around various spools or pulleys. Subsequently, as part of the process, the annealed wire is then usually cooled by passing the heated wire through some water.
Water cooling of the annealed wire has several drawbacks, however. First, as the heated wire is well above the boiling temperature of water to begin with, the actual heat transfer between the wire and the water is difficult to predict or measure accurately and some metals, such as stainless steel, require close control of this quench time/temperature relationship in order to maintain consistent wire quality. In addition, when the annealing is done by means of electricity, the annealed portion of the wire or "hot leg" must be of fixed length in order to accurately control the annealing process in terms of time and temperature. When a water quench is used, this leg is considered to end at the surface of the water. This is not precisely accurate, particularly in view of the imprecise way the heat flows from the wire to the water, which is boiling off into stream as a result of its contact with the hot wire.
Also, the water quench method of cooling an annealed wire is not as fast as desired, and in the case of wires with multiple strands, some water will become lodged between the strands. This water is difficult to remove, and it will interfere with subsequent processing of the wire.
Accordingly, an object of this invention is to provide an apparatus for and method of cooling annealed wire without direct water contact.
Another object of the invention is to provide such an apparatus and method which is faster and more accurately calculated than the water quench method.
Another object of the invention is to provide such an apparatus and method by which anneal quality may be maintained at a consistent level.
Another object of the invention is to provide an apparatus for cooling an annealed wire as part of one of the electrical contacts for the electrical annealing process.